Nginx and Apache with HAProxy

After reading some similar questions I didn't found the exact solution for me :-(

I've one Load Balancer with HAProxy at the first machine, then I've two webservers, both of them with Nginx and Apache2 to server static and dynamic content.

The strange is that, using Curl, Curl http://IP/lb.php (it's a script to give me the IP addreses), HAProxy statistics shows me that load balancing is working great.

But when I'm using the browser to get that website/page, I can see in HAProxy statistics that HAProxy isn't doing load balancing, it's possible to see in and out data only in webserver1 as I conclude it's only been used that webserver.